The present invention relates generally to the field of solenoids. More specifically, the present invention relates to the field of solenoids having control circuits.
A solenoid is a device having a coil of wire and a metal core. Often used as a switch, the solenoid has two terminals extending from its package which are connected to either end of the coil of wire. When current is supplied through the coil of wire from one terminal to the other, a magnetic field causes the metal core to slide along a coil axis. A controller is provided in a separate package to selectively regulate current through the coil of wire.
Solenoids are used in a wide variety of applications, for example, to turn hydraulic valves on and off. In one application, solenoids are used to actuate hydraulic valves to control the header of an agricultural vehicle, such as, a harvester. On a harvester, solenoids are used to drive hydraulic valves which in turn regulate a flow of hydraulic fluid to hydraulic cylinders which, in turn, regulate the height of a header with respect to ground. Thus, the operator may command the header through control circuitry to raise or lower the header during harvesting depending on such factors as the terrain, the type of crop, etc.
One drawback of such a system is the amount of control circuitry needed to drive the solenoids. For example, for a system with multiple independently-controllable headers, a controller having various analog and/or digital inputs and outputs must be fabricated, programmed, and mounted to the harvester along with the necessary data wires, cables, etc. Such a system is prone to result in loose wires, and in any event involves a great deal of cost and complexity.
Accordingly, what is needed is a solenoid which reduces the need for complex control circuitry. Further, what is a needed is a solenoid which can be controlled without the need for separate control circuitry.
According to one exemplary embodiment, a single package solenoid is disclosed having a package, a solenoid coil, and a control circuit. The solenoid coil and the control circuit are contained in the package. The control circuit is coupled to the solenoid coil and has a control terminal. The control circuit is configured to power the solenoid coil based on a control signal received on the control terminal.
According to another exemplary embodiment, a three-terminal solenoid is disclosed having a power terminal configured to receive a power signal, a ground terminal configured for coupling to a ground, and a control terminal configured to receive a control signal. The three-terminal solenoid further includes a circuit coupled to the power terminal, the ground terminal, and the control terminal configured to generate a magnetic field having a magnitude based on the control signal. A core is operable in response to the magnetic field.
According to yet another embodiment, a solenoid includes a package, a solenoid coil, and a control means for powering the solenoid coil in proportional response to a control signal, wherein the solenoid coil and the control means are contained in the package.
According to still another exemplary embodiment, a control system for controlling the position of a header of an agricultural vehicle with respect to the ground is disclosed. The control system includes a transducer coupled to the header configured to sense the position of the header with respect to the ground and to generate a header position signal. The control system further includes a single package solenoid having a package, a solenoid configured to adjust the position of the header, and a control circuit coupled to the solenoid. The control circuit has a control terminal coupled to the transducer and is configured to power the solenoid based on the header position signal received on the control terminal. The solenoid and the control circuit are contained in the package.